Aromatic esters and process of making same.



UNITED STATES Patented December 29, 1903.

PATENT OFFICE.

AROMATIC ESTERS AND PROQESS OF MAKING SAM E.

SPECIFICATION forming part of Letters Patent No. 748,101, dated December 29, 1903.

Application filed April 20, 1903. Serial No. 163,551. (Specimens) 7 To all whom it may concern.-

Be it known that I, EDUARD RITSERT, a subject of the German Emperor, residing and having my post-office address at Gutleutstrasse, Frankfort-on-the- Main, Germany, have invented certain new and useful Improvements in Aromatic Esters, of which the following is a specification.

The others of certain aromatic amidocarbonic acids have lately been much used as efiective anesthetics, yet their general application has been limited to a'certain degree by the circumstance that these others are insoluble in water, while the soluble salts of them hitherto described have proved strongly irritating. My invention is based on the discovery that these ethers yield well-defined compounds with the aromatic sulfonic acids,

which are sufficiently soluble in coldwater and at the same time may be applied without an injurious eifect.

In carrying out my invention the aromatic amid ocarbonic-acid ethers are either directly combined with the free sulfonic acids or the salts of both are brought to react mutually. The new com pounds can either be isolated in dry state or the resulting solution can be used as such. These different methods are illustrated by the following examples:

I. Paradmtdobenzot'c acid-ethyZcther-I-m'etdbe'nzenedisulfonic acid-One hundred and eighty-five grams of paraamidobenzoic acidethylether are dissolved in a hot solution of metabenzenedisulfonic acid containing one hundred and nineteen grams of the acid in about seven hundred and fifty cubic centimeters. On cooling the surplus of the ether separates out. The filtered liquor is then boiled again and having been sufficiently concentrated yields white prismatic crystals, the analysis of which agrees with the formula:

se l: 1) coocgs 1 0 H so,H 3 6 NH, 4

thopheu'oZ-sulfonic acid-If a solution of two hundred grams of the hydrochlorid of paraamidobenzoic acid-ethylether in one thousand cubic centimetersof water he added to a hot aqueous solution of two hundred and fifteen grams of the sodium salt of orthophenol-sulfonic acid in two thousand cubic centimeters, white needles separate out 011 cooling, which melt at 188 to 191 centigrade. By recrystallizing the melting-point is raised to 20l to 203. The orthophenol sulfonic acid salt of the paraamidobenzoic acid ethylether on 1) NH, 1 o H c H Q so,H 2 coooni, 4

is soluble in cold water, easily soluble in hot water or alcohol.

III. Metadmidoparaoos'ybcnzotc ucz'dmethylether-l-paraphenol sulfonic acid. This compound is obtained by dissolving one hundred and fifty grams of metaamidoparaoxybenzoic acid-methylether in a hot solution of one hundred and seventy-five grams of paraphenol-sulfonic acid in seven hundred and fifty cubic centimeters of water:

on 1 cocoa, 1

NH, (3 OH 4 white needles which melt at 219 to 221.

I V. Paradmt'dobeuzoic acidethyZether-lanisol-sulfon'ic acid.Anisol is heated with the equivalent weight of sulfuric acid for two hours on the water-bath, and the mixture resulting is diluted with about the same quan tity of water. Paraamidobenzoic acid-ethylether (one molecule) is then added to the hot solution. On cooling glittering needles are obtained, melting at 188 centigrade, which are slightly soluble in cold, easily soluble in hot water.

V. Aqueous solution of the phencl-sulfonicacid salt of paradmidobeuzoic acid ethylether.-'lhe mixture of ortho and para phenol sulfonic acid resulting by treating carbolic acid with cold sulfuric acid is liberated from unchanged carbolic and sulfuric acid by isolating the dry sulfonic-acid lead or baryta salt-s, redissolving the same and exactly precipitating the metal by sulfureted hydrogen in the one or by sulfuric acid in the other case. The aqueous solution of the free phenol-sulfonic acids thus obtained is then titrated with standard soda, solution and diluted till containing about two per cent. of acid.

The cold solution is saturated with paraamidohenzoic acid ethylether, and the surplus .of the latter having been filtered off is ready for use.

If instead of the free compounds their salts are to be applied, it is best to combine the sodium salt of the sulfonic acid With the hydrochlorid of the aromatic base, the chlorid of sodium thus formed as the only secondary product of the reaction being in no way an obstacle to the direct application of the solution.

If, for instance, one hundred and ninetysix parts of weight of the sodium salt of orthophenol-sulfonic acid and 203.5 parts of weight of the hydrochlorid of metaamidoparaoxybenzoic acid methylether are dissolved each in five liters of water on mixing results a solution containing about 1.5 per cent. of the orthoform now ready for use.

The compounds produced as described are white crystals, soluble in cold water and alcohol, not soluble in ether, and can be employed in the medical art as anesthetics without injurious effect.

The same compounds are obtained by the action of the salts of the two components, for

instance, by allowing the hydrochlorid of para-amido-benzoic acid ethylether to act on the sodium, potassium, barium, or like salts of sulfocarbonic acids.

1. The herein-described process of the manufacture of soluble anesthetics which consists in causing aromatic sulfonic acids to EDUARD RITSERT.

Witnesses:

MICHAEL VoLK, ERWIN DIPPEL. 

